Air conditioning automatic control system in the h

Air conditioning automatic control system in intelligent buildings

I. Introduction

air conditioning automatic control system is an important part of intelligent building integrated system. Air conditioning automatic control equipment is an important automatic control equipment in intelligent buildings, and air conditioning equipment itself is a large energy and power consumption of buildings. Moreover, due to the application of a large number of electronic equipment in intelligent buildings, the air conditioning load of intelligent buildings is far greater than that of traditional buildings, VAV air conditioning system uses the method of changing the air supply volume to maintain a constant room temperature to adapt to different indoor loads. VAV system (VAV air conditioning) has outstanding advantages: great energy-saving potential, flexible control, and can avoid the trouble of ceiling on chilled water and condensate water; In recent years, especially with the development of computer industry, VAV air-conditioning equipment has intelligent ability. Therefore, the scope of application continues to expand, and it has been widely used in practical projects at home and abroad, especially in the United States, Japan, Hong Kong and other places

II. Introduction to air conditioning automatic control function

intelligent building air conditioning automatic control mainly includes air conditioning unit control, fresh air unit control, variable air volume terminal (VAV) control, etc. in the building. Under the monitoring and management of the building automation system, they make the temperature and humidity in the building reach the expected goals, and maintain the normal operation of the system and equipment with the lowest energy and power consumption, so as to achieve the lowest operating cost and the highest economic benefits:

2.1 air conditioning unit control air conditioning unit system includes new/return air valve driver, air duct temperature/humidity sensor, filter differential pressure alarm switch Anti freezing alarm switch, constant speed fan, electric control valve, power distribution device and air conditioning unit control and other hardware. The system includes three parts: fresh air, return air and air supply: (1) unit start/stop: when the unit is controllable, it can also be started/stopped forcibly; (2) Fan control: as an innovative model project of Sino Russian economic cooperation, the fan can be started/stopped randomly and automatically. It can also be forced to start/stop or manually start/stop beside the fan. The running time and start/stop times are accumulated, and there are fan fault alarm output network variables; (3) Temperature control: supply cold air in summer, hot air in winter, and fresh air in transition seasons to save energy. According to the deviation between the return air temperature and the set value, control the electric water valve, adjust the opening of the cold/hot water valve to maintain the return air temperature within the set range, and carry out the forced opening control of the cold/hot water valve and the manual opening control beside the machine (0 ~ 100%); (4) Humidity control: humidity control is only carried out in winter mode. When the return air humidity drops to the lower limit, control the humidification valve to open to increase the humidity content in the air; When the return air humidity rises to the upper limit, stop the humidification valve. It can carry out forced start/stop control of humidification valve and manual start/stop control beside the machine; (5) Fresh/return air valve control: open the fresh air valve to the minimum opening and the return air valve to the maximum opening in winter/summer; In the transition season, adjust the opening of the new/return air valve to adjust the temperature, and also carry out the forced opening control of the new/return air valve and the manual opening control beside the machine (0 ~ 100%); (6) Interlock control: anti freezing alarm switch and interlock control of fan, water valve and fresh/return air valve; (7) Alarm: filter blockage alarm, fan fault alarm and antifreeze switch alarm. 2.2 fresh air unit control the fresh air unit system is mainly composed of fresh air valve driver, air duct temperature/humidity sensor, filter differential pressure alarm switch, antifreeze alarm switch, electric control valve, constant speed fan, power distribution device, fresh air unit control and other hardware. The system includes fresh air and air supply: many exhibitors have said that the order number exceeds the expectation (1) unit start/stop: when the unit is controllable, start/stop; (2) Fan control: the fan is started/stopped automatically with random group start/stop, and it can also be forced to start/stop. Although the size and range of the impact test box are the same or the manual start/stop beside the machine, the running time and start/stop times are accumulated, and there are fan fault alarm output network variables; (3) Temperature control: supply cold air in summer, hot air in winter, and fresh air in transition seasons to save energy. According to the deviation between the air supply temperature and the set value, control the electric water valve, adjust the opening of the cold/hot water valve to maintain the air supply temperature within the set range, and carry out the forced opening control of the cold/hot water valve and the manual opening control beside the machine (0 ~ 100%); (4) Humidity control: humidity control is only carried out in winter mode. When the return air humidity drops to the lower limit, control the humidification valve to open to increase the humidity content in the air; When the return air humidity rises to the upper limit, stop the work of the humidification valve, and also carry out the forced start/stop control of the humidification valve and the manual start/stop control beside the machine; (5) Fresh air valve control: when the unit is running, the fresh air valve is fully open, and the forced open/close control of the fresh air valve and the manual open/close control beside the unit can be carried out; (6) Interlock control: anti freezing alarm switch and interlock control of fan, water valve and fresh air valve; (7) Alarm: filter blockage alarm, fan fault alarm and antifreeze switch alarm

2.3 variable air volume (VAV) end control function (1) fan control: the start/stop of the fan is controlled by the manual switch, and there are output network variables of the fan status; (2) Temperature control: according to the indoor temperature measurement value, adjust the opening of the air valve to keep the indoor temperature constant; (3) Humidity control: according to the indoor humidity measurement value, control the opening/closing of the water valve to keep the indoor humidity constant

III. VAV trav air conditioning system

vav air conditioning system principle: variable volume air conditioning system (VRV) uses the method of changing the air supply volume to maintain constant room temperature to adapt to different indoor loads. The key is to realize the terminal air supply device of VAV principle, especially the terminal device and the automatic control equipment of the whole VAV system. In the past 20 years or so, not only the VAV terminal device, but also the corresponding control system, Even the type of VAV air conditioning system has changed a lot, and relevant mature and important composite polyurethane rubber new products and new technologies are emerging. Due to the rapid development of VAV technology, especially the development of DDC and network technology, American scholars have put forward the new concept of trav. Trav (terminal regulated air volume) is also a VAV system like vav, Create a comfortable environment by adjusting the air volume, but trav does not use the static pressure regulation in VAV, but the terminal device directly controls the blower. Trav uses advanced control software to control the blower based on the real-time air volume demand of the terminal device. In the traditional VAV system, when the load decreases and leads to a reduction in flow, the terminal air valve is turned down to throttle, and the static pressure in the pipeline remains unchanged; In the trav system, under the same conditions, the end air valve remains open, while the static pressure of the pipeline decreases, and